The disclosure relates generally to hot melt adhesive systems, and more particularly to the application and detection of hot materials, for example, hot melt adhesives deposited on substrates, methods and systems therefor.
The non-contact detection of beads of hot adhesives on moving conveyors by using infrared sensors that detect temperature differences between the adhesive and the substrate is known generally.
U.S. Pat. No. 4,831,258 entitled “Dual Sensor Radiation Detector” discloses for example a glue bead detection system comprising a dual sensor housing two thermopiles that detect an adhesive target and the reference moving conveyor temperatures, respectively, through a common lens. The thermopile outputs are coupled to an LED bar graph display that changes with changes between the temperatures of the adhesive target and the moving conveyor. A dynamic bar graph is indicative of intermittent adhesive beads, and a relatively constant bar graph is indicative of a relatively continuous adhesive bead.
In order to precisely detect the beginnings and ends of adhesive beads and other thermal materials, the sensor must be equipped with an optical focusing device, like the common lens in U.S. Pat. No. 4,831,258, but this limits the area that may be monitored by the sensor.
An object of the disclosure is to provide novel thermal detection methods and systems.
Another object of the disclosure is to provide thermal detection methods and systems that improve upon the art.
In one embodiment, the disclosure teaches methods in hot melt adhesive detection systems comprising generally detecting separate areas of a target, for example a hot melt adhesive on a substrate, by sensing changes in temperature with thermal sensors arranged non-parallel to a direction of relative motion between the detector and the target, and summing an output of the at least two thermal sensors. In some embodiments, the summed output of the sensors may be evaluated, for example by comparing the summed output of the at least two thermal sensors with a reference.
In another embodiment, the disclosure teaches methods in thermal detection systems, for example adhesive detection systems, comprising generally generating an output signal related to heat, for example, heat radiating from a hot melt adhesive, detected with a thermal sensor, and evaluating the output signal by comparing it to a threshold generated from a reference heat profile. In one embodiment, the threshold is a variable threshold.
In another embodiment, the disclosure teaches thermal sensing systems, for example hot melt glue sensing systems, comprising at least two thermal sensors mounted in spaced apart relation, a signal summer having inputs coupled to outputs of the at least two thermal sensors, a controller having an input coupled to a output of the signal summer, wherein the controller is programmed to sample and store the output of the summer in memory.
In yet another embodiment, the disclosure teaches thermal sensing systems, for example hot melt glue sensing systems, comprising detecting a product, detecting hot melt glue disposed on the product while detecting the product, and comparing a period during which the product is detected with a period during which the hot melt glue is detected.
These and other objects, aspects, features and advantages of the present disclosure will become more fully apparent upon careful consideration of the following Detailed Description of the Invention and the accompanying Drawings, which may be disproportionate for ease of understanding, wherein like structure and steps are referenced generally by corresponding numerals and indicators.